Evolution: Animal Diversity - Part 1 Biology 155 Krilowicz Spring 2010

I. Definitions A.Taxonomy: the science of classification of living things; older schemes were constructed without regard for evolutionary relationships among organisms B. Phylogeny: the science that examines the evolutionary relationships among organisms; most taxonomic schemes in use today are based on phylogeny

II. What types of information can be used to construct phylogenetic schemes? A.Anatomy: similarities or differences in structure of modern day forms 1.Adult structures – The bones of a human arm are very similar to those in a bird wing, so probably closely related animals (homologous structures) The vertebrate limbs are very different from arthropod limbs, so these two groups are more distantly related

Various arthropods Various vertebrate forelimbs Fig. 13.5A

II. What types of information can be used to construct phylogenetic schemes? - continued A.Anatomy: similarities or differences in structure of modern day forms – continued 2. Embryonic structure – All vertebrate embryos go through very similar developmental patterns, so probably closely related animals The development of vertebrates (deuterostomes) differs from arthropods (protostomes), so these two groups are more distantly related

Two vertebrate embryos at similar stages in development Fig. 13.5B

II. What types of information can be used to construct phylogenetic schemes? - continued B. Physiology: function of present day organisms Mammal and reptile lungs function in essentially the same manner, so probably closely related animals Insects use a tracheal system to exchange gases that functions very differently from vertebrate lungs, so these two groups are more distantly related

II. What types of information can be used to construct phylogenetic schemes? - continued C. Geologic (Fossil) Record: can be used to determine – 1. Anatomy of extinct organisms 2. First appearance of currently living organisms

II. What types of information can be used to construct phylogenetic schemes? - continued D. Biochemical Information: how similar is the structure of enzymes, ribosomes, etc. among groups of organisms?; Reflects similarity in DNA because information in the genes is used to construct proteins, RNA and other biological molecules

II. What types of information can be used to construct phylogenetic schemes? - continued E. Gene (DNA) Sequence Data – how similar is the genetic material among living organisms? ultimately what scientists really want is an answer to this question to definitely construct phylogenetic trees Has recently led to a reorganization of living things into three domains versus five kingdoms

Three domain system of classification Five kingdom system of classification

III.The Taxonomic Hierarchy: Domain (three of these) Kingdom Phylum (Animals) or Division (Plants) Class Order Family Genus Species Increased relatedness = more traits in common Only group with a biological definition

Definition of a species A group of actually or potentially interbreeding organisms that are reproductively isolated* from other organisms * Either cannot mate with another organism or mating produces sterile offspring

Species names have two parts Genus species Capitalizedlower caseitalicized Usually Latin Example – Felis domesticus